Re: [Exim] [RFC] a general iplookup

On (2002/10/17 14:13), Nico Erfurth wrote:

> this could be done with an simple protocol like this
> (>> indicates outgoing and << incoming)
>
> ---exim opens socket
> >>user@???
> <<forward@???
> <<moreforwards@???
> <<|pipecommand
> <</some/mailbox
> ---sender closes socket
>
> So the input is delimited with a LF, and the output by the the end of
> the connection.
> Or something more complex like this
>
> ---exim opens socket (or uses a cached one)
> >>30 <---- this is the size of the data that follow
> >>sometext
> >>that goes over multiple lines
> >>and should be as long as the first line indicates
> <<100 <----- responsesize
> <<100 chars of response
> --- socket will NOT be closed

I'd prefer something between the two of these, where output is
terminated by something other than a socket close, but without having to
handle response length validation.

For example, you could use a double LF to terminate a response.

That way, you still get to cache connections, but without worrying about
the overhead of response length validation.

I'd also recommend allowing for keep-alives. You could implement this
easily by allowing the client to send an empty line (single LF), to
which the server is expected to respond with a null response (double
LF).

All this assumes that responses never need to return sets of items in
which one or more items may span multiple lines. Can you think of such
a case? If so, you could still go the route I'm suggesting simply by
picking another delimiter character.

Ciao,
Sheldon.